Three wildfires in California have displaced hundreds of thousands of people and destroyed thousands of homes. So far, dozens of people have been confirmed dead and hundreds more are missing.

Vast expanses of land have been scorched in Northern California by the Camp Fire — the deadliest and most destructive wildfire in the state’s history — and in Southern California by the Woolsey and Hill Fires.

Here’s how you can help.

Remember to do your research on a charity’s reputation for using donations effectively. Charity Navigator is a good source to consult. Also, remember that sending money is almost always the most efficient way to help in a disaster, according to the Center for International Disaster Information, part of the United States Agency for International Development. If volunteers on the ground end up with a mountain of donated goods, they’ll have to spend time sorting through them rather than buying exactly what’s needed.

There are also multiple crowdfunding efforts for victims of the California fires. GoFundMe has organized a page that catalogs the relief efforts in Northern and Southern California. It includes links to donate to families who have lost their homes.

Google is collecting donations to help those affected by the wildfires in Southern California. It will funnel the donations to the Center for Disaster Philanthropy, which will distribute the money to local nonprofits.

Additionally, Airbnb has launched a program that asks people to open their homes to those affected by the fires. Until Nov. 29, the company is allowing residents to mark their homes as a place for evacuees and aid workers to stay for free.

For more information about how to help, call CJ Suppression at 888-821-2334 or visit the website at www.cjsuppression.com.